76 CARTILAGE. 



congelation is not in reality owing to an admixtm-e of gelatin derived from 

 fibrous tissue not duly separated from the cartilage. Like gelatin, chondiin is 

 thrown down from its solutions by tannic acid, alcohol, ether, creasote, and 

 con-osive sublimate, and not by j^russiate of potash. It differs from gelatin in 

 being precipitated by the mineral and other acids, the acetic not excepted ; 

 also by alum, sulphate of alumina, persuli^hate of ii-on. and acetate of lead ; 

 the precipitates being soluble in an excess of the respective precipitants. The 

 temporary cartilages are resolved into a matter which has the chemical reactions 

 of chondrin, but does not gelatinise. 



The following analyses are by Hoppe Seyler : 



In 100 parts. 

 Water. Solids. 



Organic. Inorganic. 



Costal Cartilage . , . G7-G7 30-13 2-20 



Articular Cartilage . , . 73'.59 24'87 I'oi 



The ashes from Costal Cartilage were found to contain in 100 parts : 

 Sulphate of potash . . 26'C6 

 Sulphate of soda . . ii'Sl 



Chloride of sodiiun . . 6'11 



Phosphate of soda . . 8'-12 



Phosjjhate of lime . . 7*88 



Phosphate of magiiesia . 4-.j5 



Frommherz and G-ugert obtained a small percentage of iron and considerable 

 quantities of the carbonates of lime and soda. 



Development of Hyaline Cartilage. — The parts of the embryo 

 which are about to become cartilages are made up at first of the common 

 embryonic cells from which the tissues generally originate. The cell- 

 contents clear up, the nucleus becomes more visible, and the cells, 

 mostly of polygonal outline, appear surrounded Ijy clear lines of pel- 

 lucid substance, forming as it were a network of bright meshes inclosing 

 them, but in reality consisting of the cohering capsules of the con- 

 tiguous cells, and constituting all tliat exists of the matrix at this time.* 

 Glycogen appears at an early period in the protoplasm of cartilage-cells. 

 Eouget found it in the sheep's embryo of two months, both in ossifying 

 cartilage and in the cartilages of the trachea. 



The subseqnent changes consist in enlargement and multiplication 

 of the cells and development of the intermediate matrix. 



The process is commonly described as follows, but it is necessary to 

 mention that all the successive steps here described and represented (see 

 fig. 46) have not been actually traced : — The cartilage-cells first divide, 

 a species of capsule being formed round each of the young cells (b), 

 Avhiist the old one inclosing them becomes blended with the intercellular 

 matrix, and is no longer traceable (c). 



The new cells, in turn, divide in the same way, so as to make a group 

 of four, each of which is surrounded by its own capsule (d), whilst the 

 capsules of the first descent (secondary) blend with the matrix (e) like 

 their predecessor. 



It is doubtful how the capsule is produced ; whether excreted by the cell which 

 it afterwards incloses, as held by Kolliker ; or formed by conversion of a superficial 

 laj-er of the protoplasm of the cell-body, as taught hy Max Schultze ; or a primarily 

 independent deposit around the cells. However this may be. there is at iii-st no 

 matrix biit what is made uji of the ample capsules. In further gro^vth there is 

 a di^erence, according as the cells do or do not undergo frequent division. In the 



* Cartilages, whicli retain this condition throughout life, have been termed " parenchy- 

 matous." A good example of tins is found in tlie cartilage of the mouse's ear, and in 

 that which composes tlie notochord of the embi^o. 



